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- Leukemia facts
- What is leukemia? What are the different types of leukemia?
- What causes leukemia? Is leukemia hereditary?
- What are leukemia risk factors?
- What are leukemia symptoms and signs?
- How do physicians diagnose leukemia?
- What is the treatment for leukemia?
- What are complications of leukemia?
- What is the prognosis of leukemia?
- How often does leukemia recur?
- Is it possible to prevent leukemia?
- What support groups are available for people with leukemia?
- What research is being done on leukemia?
What causes leukemia? Is leukemia hereditary?
The exact cause of leukemia is not known, but it is thought to involve a combination of genetic and environmental factors. Leukemia cells have acquired mutations in their DNA that cause them to grow abnormally and lose functions of typical white blood cells. It is not clear what causes these mutations to occur. One type of change in the cells' DNA that is common in leukemias is known as a chromosome translocation. In this process, a portion of one chromosome breaks off and attaches to a different chromosome. One translocation seen in almost all cases of CML and in sometimes in other types of leukemia is an exchange of DNA between chromosomes 9 and 22, which leads to what is known as the Philadelphia chromosome. This creates an oncogene (cancer-promoting gene) known as BCR-ABL. This change in DNA is not inherited but occurs sometime in the life of the affected individual.
Most cases of leukemia are not believed to be hereditary, but certain genetic mutations and conditions can be passed along to offspring that increase the chances of developing leukemia. A condition known as Li-Fraumeni syndrome is characterized by an inherited mutation in a tumor suppressor gene known as TP53, and individuals with this condition have an increased risk of leukemia and other cancers. Other hereditary conditions that can increase the risk of developing leukemia include Down syndrome, neurofibromatosis type 1, ataxia telangiectasia, and Noonan syndrome.
What are leukemia risk factors?
Exposure to radiation is known to increase the risk of developing AML, CML, or ALL. Increases in leukemia were observed in people surviving atomic bombs. Radiation therapy for cancer can also increase the risk of leukemia. Exposure to certain chemicals, including benzene (used commonly in the chemical industry), increases the risk of leukemia. Cigarette smoking is known to increase the risk of developing AML.
Certain genetic disorders can increase the risk; Down syndrome, Li-Fraumeni syndrome, and other medical conditions can increase the risk of developing leukemia. Blood disorders known as myelodysplastic syndromes confer an increased risk of developing AML. Human T-cell leukemia virus type 1 (HTLV-1) is a virus that causes a rare type of leukemia. Certain chemotherapy drugs for cancer can increase the risk for AML or ALL.
Having risk factors does not mean that a person will definitely get leukemia, and most people with risk factors will not develop the disease. Likewise, not everyone who develops leukemia has an identifiable risk factor.